Проект Eclipse / Maven отсутствует необходимая библиотека / отсутствующий артефакт

Я получаю следующие ошибки в Eclipse с помощью Maven:

Missing artifact org.eclipse:swt:jar:3.7.
Project 'davmail' is missing required library: '/home/buzz-dee/.m2/repository/org/eclipse/swt/3.7.0/swt-3.7.0.jar'

большинство библиотек находятся, как вы можете видеть на приведенном выше изображении, но некоторые нет. Но файлы в нужном месте.:

ls ~/.m2/repository/org/eclipse/swt/3.7.0/
swt-3.7.0.jar.lastUpdated  swt-3.7.0.pom.lastUpdated

это частичный pom.xml:

<?xml version="1.0" encoding="ISO-8859-1"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>davmail</groupId>
    <artifactId>davmail</artifactId>
    <packaging>jar</packaging>
    <version>4.6.1</version>
    <name>DavMail POP/IMAP/SMTP/Caldav/Carddav/LDAP Exchange Gateway</name>
    <organization>
        <name>Mickaël Guessant</name>
    </organization>
    <repositories>
        <repository>
            <id>central</id>
            <name>Maven Repository Switchboard</name>
            <layout>default</layout>
            <url>http://repo1.maven.org/maven2</url>
            <snapshots>
                <enabled>false</enabled>
            </snapshots>
        </repository>
        <repository>
            <id>xwiki</id>
            <layout>default</layout>
            <url>http://maven.xwiki.org/externals</url>
            <snapshots>
                <enabled>false</enabled>
            </snapshots>
        </repository>
    </repositories>
    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>3.8.1</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.apache.jackrabbit</groupId>
            <artifactId>jackrabbit-webdav</artifactId>
            <version>2.4.3</version>
            <exclusions>
                <exclusion>
                    <groupId>org.apache.jackrabbit</groupId>
                    <artifactId>jackrabbit-jcr-commons</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>xml-apis</groupId>
                    <artifactId>xml-apis</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.3.1</version>
        </dependency>
        <dependency>
            <groupId>commons-httpclient</groupId>
            <artifactId>commons-httpclient</artifactId>
            <version>3.1</version>
        </dependency>
        <dependency>
            <groupId>commons-codec</groupId>
            <artifactId>commons-codec</artifactId>
            <version>1.3</version>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.16</version>
            <exclusions>
                <exclusion>
                    <groupId>javax.jms</groupId>
                    <artifactId>jms</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>com.sun.jdmk</groupId>
                    <artifactId>jmxtools</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>com.sun.jmx</groupId>
                    <artifactId>jmxri</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>javax.mail</groupId>
            <artifactId>mail</artifactId>
            <version>1.4.3</version>
        </dependency>
        <dependency>
            <groupId>javax.activation</groupId>
            <artifactId>activation</artifactId>
            <version>1.1.1</version>
        </dependency>
        <dependency>
            <groupId>org.eclipse</groupId>
            <artifactId>swt</artifactId>
            <version>3.7.0</version>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>servlet-api</artifactId>
            <version>2.4</version>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>net.sourceforge.htmlcleaner</groupId>
            <artifactId>htmlcleaner</artifactId>
            <version>2.2</version>
        </dependency>
        <!-- included in Java 1.6, needed with Java 1.5 -->
        <dependency>
            <groupId>org.codehaus.woodstox</groupId>
            <artifactId>woodstox-core-asl</artifactId>
            <version>4.1.2</version>
        </dependency>
        <dependency>
            <groupId>org.samba.jcifs</groupId>
            <artifactId>jcifs</artifactId>
            <version>1.3.14</version>
        </dependency>
        <dependency>
            <groupId>net.freeutils.charset</groupId>
            <artifactId>jcharset</artifactId>
            <version>1.3</version>
        </dependency>
        <dependency>
            <groupId>org.boris.winrun4j</groupId>
            <artifactId>winrun4j</artifactId>
            <version>0.4.5</version>
        </dependency>
    </dependencies>
    <pluginRepositories>
        <pluginRepository>
            <id>apache.snapshots</id>
            <url>http://repository.apache.org/snapshots</url>
            <releases>
                <enabled>false</enabled>
            </releases>
        </pluginRepository>
    </pluginRepositories>
    <build>
        <sourceDirectory>src/java</sourceDirectory>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.5</source>
                    <target>1.5</target>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-site-plugin</artifactId>
                <version>2.2</version>
            </plugin>
        </plugins>
    </build>
</project>

что может быть не так?